


The Yin-Yang Master: Journal of Mysterious Cases

by The_Sassiest_Trixster



Series: 晴雅集 | The Yin-Yang Master: Dream of Eternity [4]
Category: S.C.I.谜案集 | S.C.I. Mystery (TV), 晴雅集 | The Yin-Yang Master (2020)
Genre: Angst and Hurt/Comfort, Angst with a Happy Ending, Blood and Injury, Blood and Violence, Canon-Typical Violence, Crossovers & Fandom Fusions, Graphic Description of Corpses, Hurt/Comfort, M/M, Originally Posted on Tumblr, Tumblr Ask Box Fic
Language: English
Status: Completed
Published: 2021-02-22
Updated: 2021-02-22
Packaged: 2021-03-12 03:28:27
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, No Archive Warnings Apply
Chapters: 1
Words: 6,017
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29628408
Author URL: https://archiveofourown.org/users/The_Sassiest_Trixster/pseuds/The_Sassiest_Trixster
Summary: It wasn’t every day that Bai Yutong and Zhan Yao ran through the streets of downtown Beijing chasing after a suspect but when they did, they hated it.  It’s not that they couldn’t keep up with the suspect (Bai Yutong might have been a little faster than Zhan Yao, but Zhan Yao could hold his own), but it’s that they had to weave in and out of crowds, shove past people to get closer to the suspect, and as soon as they get close enough, the suspect disappears.
Relationships: Bai Yutong/Zhan Yao, Qingming/Boya
Series: 晴雅集 | The Yin-Yang Master: Dream of Eternity [4]
Series URL: https://archiveofourown.org/series/2157513
Comments: 2
Kudos: 24





	The Yin-Yang Master: Journal of Mysterious Cases

**Author's Note:**

> Inspired by: Hi, so here I am again lol. I'm a bit shy to ask but I'm craving for both Qing Ming x Boya and Bai Yutong x Zhan Yao fanfic. So may I ask for a crossover fic about them, probably both cp are hunting down a criminal/demon that harms people. Angst angst angst and then HE please. Thank you.

It wasn’t every day that Bai Yutong and Zhan Yao ran through the streets of downtown Beijing chasing after a suspect but when they did, they hated it. It’s not that they couldn’t keep up with the suspect (Bai Yutong might have been a little faster than Zhan Yao, but Zhan Yao could hold his own), but it’s that they had to weave in and out of crowds, shove past people to get closer to the suspect, and as soon as they get close enough, the suspect disappears.

“Damn it!” Bai Yutong spat after running almost a good few blocks after their suspect. Zhan Yao, who was at his side, panted heavily, leaning up against a nearby wall. 

“Fuck” he breathed. He wasn’t entirely fond of chasing after suspects (just like he wasn’t entirely fond of exercise).

“You okay, Cat?” Bai Yutong called out, looking back at him. Zhan Yao cracked open an eye and sighed.

“Yeah…just a little out of breath” he replied. Bai Yutong smirked.

“You did good though, keeping up. Normally you can’t keep up with me on chases like these” he teased. Zhan Yao opened both eyes this time and narrowed them at him before he lashed out, nearly hitting Bai Yutong with his foot.

“Shut up. I have to be in shape if I want to keep up with the likes of you” he grumbled. Bai Yutong smirked.

“Oh? Are you saying you’re working out to keep up with me?” he teased. Zhan Yao huffed.

“Shut up, Mouse. Let’s get back to S.C.I. Maybe they can tell us more about our suspect” he stated. Bai Yutong hummed.

“Let’s hope so” he murmured. As they continued to head back, Zhan Yao looked up and noticed the suspect darting down an alley. His eyes widened and he immediately took off, making Bai Yutong look at him in shock.

“Yao!” he shouted. 

“Hurry up, Yutong!” Zhan Yao shouted, still chasing after the suspect. Bai Yutong growled.

“Damn it, Cat” he murmured, racing after Zhan Yao. The two detectives continued to run through the street, weaving past people before turning and heading down the alley where they thought the suspect went. 

“Damn it, where did he go?” Zhan Yao hissed before he saw the suspect running down the adjacent alley.

“Stop! Police!” he shouted, running after the suspect, Bai Yutong right on his heels. They continued to chase the suspect until he suddenly ran through a brick wall, making Zhan Yao stop and blink in confusion.

“What the—” he whispered, just as Bai Yutong ran over to him.

“Where’d he go?” he demanded. Zhan Yao was silent, still stunned by what happened.

“Cat?” Bai Yutong asked, looking over at his partner. Zhan Yao blinked before he pointed to the wall.

“He went…through there” he whispered. Bai Yutong looked over at the wall and blinked.

“Through…the wall?” he asked. Zhan Yao nodded. Bai Yutong was quiet before he looked over at Zhan Yao.

“Are you sure all the running hasn’t gotten to your head? Are you light-headed?” he asked. Zhan Yao turned and glared at him.

“Do I look light-headed to you?” he snapped before he took a step forward and began running his fingers over the brick.

“What are you doing?” Bai Yutong asked, stepping forward to join Zhan Yao at the wall. Zhan Yao was quiet as he continued to run his fingers over the brick before his hand suddenly went through, causing him to stumble and lose his balance.

“Cat!” Bai Yutong exclaimed as Zhan Yao fell through the wall; Zhan Yao reaching out and grabbing onto his wrist, pulling him through as well.

~*~*~*~*~*~

Both men crashed through the…portal and arrived in a strange world, both of them dressed in long flowing robes. 

“Ugh, Yutong, get off me. You’re crushing me” Zhan Yao grumbled, giving Bai Yutong a nudge. Bai Yutong groaned and pushed himself to his feet before he held out a hand, which Zhan Yao took. Once they were both standing, they looked at each other and blinked.

“What…what happened to our clothes?” Zhan Yao murmured. Bai Yutong shook his head as he looked around.

“Where the hell are we?” he wondered. Zhan Yao looked up and frowned as he studied his surroundings.

“Ancient China…I think” he murmured. Bai Yutong hummed.

“Would explain the clothes” he agreed, motioning to the outfits that they were wearing. Zhan Yao looked at his robes before he hummed as well.

“We should at least try and go find our suspect” he declared. Bai Yutong nodded and soon both men were walking through the street, studying the world that they had entered.

“So this is Ancient China…I always wondered what it would be like to live in Ancient China” Bai Yutong mused. Zhan Yao looked over at him and raised an eyebrow.

“Really?” he asked. Bai Yutong shrugged as Zhan Yao smirked.

“I didn’t take you for a history nerd” he teased. Bai Yutong huffed and punched Zhan Yao in the arm, making him hiss.

“Asshole” he grumbled. Bai Yutong chuckled, just as their suspect came running towards them. Bai Yutong’s eyes widened and he quickly pulled out his gun (which he surprisingly still had in Ancient China).

“Freeze” he shouted. The suspect just laughed as he pulled out a sword and slashed, causing Zhan Yao and Bai Yutong to dodge out of the way so that they didn’t get cut.

“Bastard” Bai Yutong growled before he fired his gun, just as an arrow went flying past his face, causing him to turn and look to see a tall man with light skin, brown eyes, and long dark brown hair dressed in all black running towards their suspect, a bow and arrow in his hands.

“Watch it!” Bai Yutong shouted, glaring at the man. Because of his shout, the suspect quickly dodge out of the way, avoid both bullet and arrow. Since he dodge the attack, the man in black turned towards Bai Yutong, growling.

“You” he snarled as he placed his bow on his back and pulled out a sword that was strapped to his back. He then raised the sword, slashing down when Zhan Yao rushed in front of Bai Yutong, the sword slashing him on the arm. He let out a cry of pain and clutched at his arm, feeling the warm blood seeping through his fingers.

“Zhan Yao!” Bai Yutong shouted before he growled and pointed his gun at the man, letting off a shot. However, a portal suddenly opened before him, causing the bullet to travel through it, disappearing to a different world

“The hell?!” he exclaimed as he looked over to see a tall man with light skin, brown eyes, and long dark brown hair dressed in white standing next to the man in black.

“Oh dear…Boya what did you do?” he murmured, looking over at the man in black.

“They let the demon escape” the man, Boya, growled. The other man huffed, a small smile on his face, and shook his head.

“And you went and hurt one of them?” he asked before he looked over at Bai Yutong and Zhan Yao.

“I apologize. I can take a look at your friend’s arm, if you’d like” he offered. Bai Yutong nodded as the man in white smiled.

“Great. Follow us, please” he instructed, motioning for Bai Yutong and Zhan Yao to follow him and Boya back to a rather fancy home. When they arrived, the man in white motioned for Zhan Yao to sit down. Bai Yutong, of course, had to help him, as he was bleeding rather profusely and he was afraid that Zhan Yao would pass out if he didn’t help him. Once he was sitting, the man in white knelt down beside Zhan Yao and grabbed the torn part of the sleeve, ripping it off so that he had easier access to the wound.

“Aish Boya…that damn sword of yours. If you had cut any deeper, you would have severed the muscle” he scolded, glaring up at Boya. Boya huffed.

“He wouldn’t have gotten hurt if he hadn’t stepped in front of him” he grumbled, motioning with a thumb to Bai Yutong. Bai Yutong growled and pulled out his gun, pointing it at Boya again.

“I should a bullet in you for hurting Zhan Yao” he spat. 

“Yutong” Zhan Yao murmured, making Bai Yutong and Boya look over at him as he looked back at them.

“Don’t. It was an accident” he murmured. 

“But!” Bai Yutong exclaimed.

“I’m fine” Zhan Yao assured, just as the man in white finished bandaging him.

“You should alright now, just be careful not to open your wound” he instructed before he cleared his throat.

“I haven’t introduced myself. My name is Qingming and this is Boya” he introduced, motioning to Boya, who dipped his head. Zhan Yao and Bai Yutong dipped their heads to them as Zhan Yao cleared his throat.

“I’m Dr. Zhan Yao and this is Police Sergeant Bai Yutong. We’re the leaders of S.C.I., the Special Crimes Investigation team” he explained. Qingming and Boya frowned.

“S.C.I.? I don’t believe we’ve heard of them before” Qingming stated before he looked over at Boya.

“You’re more traveled than I am, A-Ya. Have you?” he asked. Boya shook his head.

“I haven’t” he replied. Bai Yutong huffed.

“Well, that would be because we’re not from this time period. We’re from the future” he explained. Qingming and Boya blinked in surprise.

“The future?” they repeated before Boya motioned to the gun in Bai Yutong’s hand.

“That would explain the strange thing in your hand” he mused. Bai Yutong held up the gun.

“This? You mean my gun?” he asked. Boya nodded. Bai Yutong then held it out to him and Boya took it gingerly, looking it over. While he was looking at the gun, Qingming looked over at Zhan Yao.

“How did you get here? Well, a better question to ask would be, what _brought_ you here?” he asked. Zhan Yao looked back at him and sighed.

“We were chasing a suspect and while we were chasing them through an alley, they slipped through a brick wall. We thought that was strange so I went to investigate and I guess we sort of fell through a portal?” he explained. Qingming hummed. 

“So a demon escaped this world and made it to your world…this is bad” he murmured before he looked up at Boya.

“Don’t you think so?” he asked. Boya nodded as he handed Bai Yutong’s gun back to him.

“Yes…we don’t know what kind of terror they’ve been getting into the modern world, if that is what your world is called” he stated, looking over at Bai Yutong. Bai Yutong nodded.

“The modern world is correct, yes” he replied before he huffed.

“What do you know about this…demon?” he asked. Qingming and Boya shook their heads.

“Not much…what do you know about them?” Boya asked. Zhan Yao sighed.

“Probably about as much as you…” he murmured before his eyes widened and he looked at Bai Yutong.

“Yutong—” he started. Bai Yutong looked over at him and raised an eyebrow.

“What are you thinking, Kitten?” he asked. Zhan Yao didn’t even have to say anything, he just stared at Bai Yutong and Bai Yutong huffed before he sighed.

“Fine. It couldn’t hurt” he agreed before he walked over to Zhan Yao and held out a hand. Zhan Yao smiled softly and reached out, taking Bai Yutong’s hand, allowing himself to be helped up. Once he was standing, he looked over at Boya and Qingming.

“If you don’t mind coming with us, maybe we can work this case out together?” he offered. Boya and Qingming looked at each other before they looked back at Bai Yutong and Zhan Yao.

“We don’t mind” Qingming answered. Bai Yutong smirked.

“Good. Follow us” he ordered before he and Zhan Yao walked out of the room, leaving Boya and Qingming to stare after them.

“What a strange couple…” Boya murmured. Qingming chuckled.

“But they remind you a bit of us, don’t they?” he asked. Boya huffed.

“Maybe” he grumbled. Qingming chuckled before he followed after Bai Yutong and Zhan Yao, Boya at his heels.

~*~*~*~*~

The four men walked through the streets when Boya’s demon hunter instinct kicked in and his eyes narrowed.

“Ming…he’s nearby” he growled. Qingming, Bai Yutong, and Zhan Yao looked over at him before Qingming sighed.

“Where?” he asked. Boya pointed in front of him.

“There” he growled. Bai Yutong, Zhan Yao, and Qingming turned to see the suspect (demon), standing before them, a dark smile on his face.

“Bastard. Get back here!” Bai Yutong shouted, running towards the suspect.

“Bai Yutong!” Zhan Yao shouted, running after him. Qingming and Boya looked at each other before they rushed after the two men, who ran after the demon, who just laughed and jumped through thin air, disappearing.

“He disappeared!” Zhan Yao exclaimed.

“He probably went back to our world!” Bai Yutong shouted before he ran towards the place where the demon disappeared through and ran through it, disappearing as well.

“Yutong!” Zhan Yao shouted, running after his partner, disappearing through thin air as well.

“Huh…so there really is a portal” Qingming murmured, just as Boya grabbed him by the wrist.

“Hold on, Ming. We’re about to do something dangerous” he declared as he ran towards where Bai Yutong and Zhan Yao disappeared, disappearing through the portal, dragging Qingming with him.

~*~*~*~*~

Back in the modern world, Zhan Yao and Bai Yutong were dressed in their normal outfits, Bai Yutong in his white pants, white high tops, white dress shirt, black tie, and white suit jacket and Zhan Yao in his navy blue turtleneck, navy blue pants, black boots, and long navy blue overcoat. 

“Ugh…so this is what time travel feels like” Bai Yutong grumbled, shaking his head. Zhan Yao huffed.

“It’s not pleasant” he agreed before he turned and looked over his shoulder, his eyes widening slightly.

“Yutong” he called out, making Bai Yutong look up before he looked over his shoulder as well to see Boya and Qingming standing before them, dressed in modern clothing. Boya had the same style as Bai Yutong, except everything for him was in black and his hair was still long and tied up in a high ponytail. Qingming was dressed in black pants, a soft cream sweater, black boots, and a long cream coat, his long hair in a half-up, half-down ponytail.

“They look so different” Bai Yutong murmured. Zhan Yao nodded as Qingming and Boya looked down at themselves before looking at one another.

“Oh…” Qingming murmured.

“Welcome to the modern world” Bai Yutong called out, grabbing Qingming and Boya’s attention. Both men turned to see Bai Yutong smirking slightly.

“If you’ll just follow us, we’ll take you to S.C.I. and we can talk this case over with our team” he stated. Qingming and Boya nodded, following after Bai Yutong and Zhan Yao as they walked out of the alley.

~*~*~*~*~

When they arrived at the police department, Qingming and Boya looked up at the building with wide eyes.

“This is where you work?” Qingming whispered. Zhan Yao hummed.

“It is. Now here” he stated, holding out two badges to them. Qingming and Boya frowned and reached out, taking the badges.

“What is this for?” Boya asked, as he looked at his badge.

“It’s a visitor’s pass. You need it to get in” Bai Yutong explained as he and Zhan Yao slipped on their own badges before heading inside the building. Qingming and Boya quickly followed their example and slipped their badges over their heads before following after them. Once they got past the gate, they got into the elevator and headed up to the 11th floor, where the S.C.I. unit was located. 

“Everything’s so white here” Boya grumbled.

“Hurts your eyes, doesn’t it?” Zhan Yao teased, a small smile on his lips. Boya huffed as Qingming chuckled, the four of them walking through the sliding glass doors.

“Bai Sir, welcome back! Did you catch the suspect?” Bai Chi asked, looking at his cousin with wide eyes. Bai Yutong narrowed his eyes.

“I wouldn’t be up here if I caught him” he snapped. Bai Chi laughed nervously as Ma Han looked over at Boya and Qingming.

“Who’re they?” she asked. Bai Yutong and Zhan Yao looked over at Qingming and Boya before Bai Yutong cleared his throat.

“Inspectors Qingming and Boya. They have some information on the case that we’re working on and they came to help” he explained. The other S.C.I. team members looked over at Qingming and Boya, almost as if they were studying them, before Zhan Yao cleared his throat.

“It’s rude to stare” he scolded. The others turned and looked at him before they dipped their head.

“Sorry Dr. Zhan” Zhao Fu apologized. Bai Yutong huffed as he crossed his arms.

“Jiang Ling. Let’s go over the case and catch our inspectors up to speed, hmm?” he instructed. Jiang Ling nodded as she clicked a few keys on her keyboard, her computer screen showing up on the projector.

“For over the past week or so, multiple bodies have been popping up all over China, all females. The bodies are always mutilated, their nails are always ripped out, and it’s always a bloody mess” she explained. Qingming hummed.

“Any connections between the victims?” he asked, crossing his arms. Jiang Ling shook her head.

“Not that we can see” she replied. 

“Pull up the crime scene photos, Jiang Ling” Zhan Yao ordered. Jiang Ling nodded, and typed a few more keys on her keyboard, pulling up the crime scene photos. Bai Chi and the others looked away, but Boya and Qingming stepped closer, studying them.

“Hmm…scantily-clad clothing, dark makeup, bright red lips…are all these women prostitutes?” Boya asked, looking over at the others. The S.C.I. was quiet before they all burst out in exclamations and shouts.

“WHY DIDN’T WE NOTICE THAT SOONER?!” Ma Han screeched. 

“WE’VE BEEN ON THIS CASE FOR A MONTH, HOW DID YOU NOT NOTICE THE SIMILARITIES BETWEEN THE VICTIMS?!” Bai Yutong shouted. As Bai Yutong and his team shouted at each other, Zhan Yao pinched the bridge of his nose.

“Oh dear” he murmured. Qingming chuckled.

“Does this happen often?” he asked, walking over to stand by Zhan Yao. Zhan Yao sighed.

“Often enough” he replied before he looked over at him.

“What about your end? What do you know about this demon?” he asked. Qingming sighed.

“From what we can tell from your photos…it seems to joy and passion in killing prostitutes…can’t imagine why though” he murmured. Zhan Yao huffed.

“Well, some people are just sick. Maybe it’s a revenge sort of thing?” he offered.

“Maybe” Boya mused as he walked over to join them.

“Inspector, have you also been experiencing an odd amount of crime in your area?” Wang Shao asked, looking over at them. Qingming and Boya looked at him before Boya nodded.

“Yes, unfortunately” he answered. Bai Yutong then cleared his throat, gaining everyone’s attention.

“The inspectors, Zhan Yao, and I are going to speak in my office. If you need us for anything, knock” he ordered. He then turned on his heels, Zhan Yao instinctively following him, Qingming and Boya following after them. Once they were gone, the S.C.I. team looked at each other.

“It’s like looking in a fucking mirror” Zhao Fu murmured. 

“More like a fucking carbon copy” Wang Shao corrected.

“The same color scheme and everything” Ma Han agreed. Bai Chi hummed.

“I wonder how they met…Bai Sir and Dr. Zhan don’t like to collaborate with other stations…or other units” he mused. Jiang Ling huffed.

“Well obviously they look alike, so that might be a benefit” she mused.

“Hey!” a voice shouted, making everyone flinch and look over to see Bai Yutong sticking his head out of his office.

“We can hear everything you’re saying. Please do something useful with your time rather than discuss the inspectors” he instructed. Everyone bowed before they quickly got back to work, allowing Bai Yutong to stick his head back inside his office and shut the door.

~*~*~*~*~

Inside his office, Bai Yutong let out a heavy sigh and ran a hand through his hair before he looked at the others.

“Sorry, about that” he apologized. Qingming smiled and shook his head.

“It’s alright” he assured as Boya crossed his arms.

“So this demon is taking revenge on prostitutes…is that what we’re getting at?” he asked. Zhan Yao nodded.

“I believe so. Now we just need to figure out motive” he replied. 

“What could his motive be?” Qingming asked. Bai Yutong shrugged as he walked over to his desk and leaned against it.

“Could be like you said, revenge. Maybe a prostitute rejected him and now he just targets all of them. Or it could just be that he’s a psychopath who enjoys killing innocent people” he replied. Zhan Yao crossed his arms.

“Do demons enjoy killing for fun?” he asked. Boya glared at him.

“What do you think?” he snapped. Zhan Yao huffed.

“We don’t have demons in the modern world. Not like the kind that you’re talking about. We just have monsters; humans who think very little of human life and enjoy making people suffer” he explained. Qingming and Boya hummed.

“Well, to answer your question, yes, demons do enjoy killing for fun. And this one seems to take a lot of pleasure in it, seeing as how many people he’s killed” Qingming mused. 

“Is it just a male that’s doing the killing? Maybe it’s a female” Bai Yutong offered. 

“Out of jealousy?” Boya asked. Zhan Yao nodded.

“That would make sense too. She may have been cheated on by a lover with a prostitute and decided to get revenge. That would fit the revenge theory” he mused. 

“It is just one person doing the killings, correct? We don’t have to search for a second party?” Qingming asked. Bai Yutong and Zhan Yao shook their heads.

“We only chased after one person” Bai Yutong replied, just as there was a knock on the door.

“Come in” Bai Yutong called out. Just then, the door opened and Ma Han poked her head in.

“Bai Sir, another body was found” she stated. Bai Yutong, Boya, Qingming, and Zhan Yao looked at her in shock.

“WHAT?!” they exclaimed. 

~*~*~*~*~

A little while later, Qingming, Boya, and the S.C.I. team arrived at the scene.

“Gongsun, Lou Tian, what’ve we got?” Bai Yutong called out as they walked over to the medical examiner, Zhe Gongsun, and Lou Tian, another S.C.I. member.

“Same as the last time. Mutilated body, torn out fingernails, bloody mess” Lou Tian answered. 

“How old is the victim?” Boya asked. Gongsun looked over at him and raised an eyebrow before he glanced at Bai Yutong and Zhan Yao.

“Inspectors who are helping us with this case” Bai Yutong explained. Gongsun nodded before he looked at Boya.

“Mid-teens. About 15” he answered. Qingming frowned.

“Were all of them teenagers?” he asked. Gongsun paused before he looked at him.

“Come to think of it, yes. They were all teenagers” he stated. Zhan Yao clenched his hands into fists.

“What the hell. Who would do that to a kid…” he hissed, gritting his teeth when he looked up and noticed the demon standing at the tunnel, grinning darkly.

“You sonavabitch!” he roared, suddenly taking off after the demon. Bai Yutong’s eyes widened and he quickly took off after him.

“Zhan Yao! Zhan Yao!” he shouted. Qingming and Boya quickly followed after them, leaving the other S.C.I. members standing there confused.

“Why did Dr. Zhan—” Wang Shao started.

“Zhan Yao doesn’t take cases that have to deal with children very well” Gongsun deadpanned. Everyone fell silent before they bowed their heads, out of respect for the victim as well as Zhan Yao.

~*~*~*~*~

Zhan Yao, Bai Yutong, Qingming, and Boya continued to run through the street, chasing after the demon. 

“Zhan Yao! Zhan Yao!” Bai Yutong shouted, but Zhan Yao ignored him, continuing to chase after the demon until they made the same turn down the alley with the portal.

“You’re not escaping this time” Zhan Yao growled, pushing himself harder until he grabbed the demon and pushed him through the portal, sending them both back to Ancient China. A few moments later, Bai Yutong, Qingming, and Boya arrived at the wall, the three men panting harshly.

“They probably went back…” Qingming panted. Bai Yutong growled.

“We need to save him” he declared as he took out his gun out of its holster.

“Let’s go” he growled. Boya and Qingming nodded before the three of them rushed into the wall, disappearing through the portal.

~*~*~*~*~

When they stepped through the portal, Bai Yutong, Qingming, and Boya found themselves to be dressed in their original clothes (well, Boya and Qingming were dressed in their original clothes, Bai Yutong was dressed in the white robes). 

“Can you sense them, Boya?” Qingming asked, looking over at Boya. Boya shut his eyes, silence falling over him before his eyes flew open.

“Found them” he whispered. He then suddenly took off, causing Bai Yutong and Qingming to follow him until they came upon a relatively empty area of the city. Before them, Zhan Yao was being pinned down, the demon on top of him, a knife blade pressed to his throat. Bai Yutong’s eyes widened and he quickly aimed his gun at the demon.

“Get OFF OF HIM!” he screamed before he fired, hitting the demon in shoulder. The impact of the shot was just enough to send the demon flying off of Zhan Yao, allowing Zhan Yao to push himself up and run over to Bai Yutong, Qingming and Boya.

“Stay here, Cat” Bai Yutong ordered before he stepped forward, repeatedly firing his gun, hitting the demon over and over again. Unfortunately, the demon just stood up, the bullets falling out of its body like the skin was pushing them out.

“What the fuck” Bai Yutong whispered, just as the demon appeared before him and grabbed him by the throat, throwing him into a nearby house. 

“BAI YUTONG!” Zhan Yao shouted as the house came crashing down. Zhan Yao’s eyes widened as Boya quickly rushed forward, drawing his sword. He then attacked the demon, who easily dodged the attacks, laughing the entire time as Boya tried to attack him. Suddenly, a portal opened up behind him and Qingming stepped out, smirking.

“Surprise” he whispered, kicking the demon in the back. The demon went flying forward and almost impaled himself on Boya’s sword but dodged at the last minute, resulting in a slice to the side. While Boya and Qingming were attacking the demon, Zhan Yao raced over to where the destroyed house was and began going through the rubble until he came across Bai Yutong, who seemed to be out cold.

“Bai Yutong. Bai Yutong!” he shouted, shaking the man’s shoulders slightly. Bai Yutong said nothing and as Zhan Yao leaned down, he heard a slight heartbeat in his chest and the softest of breathing, making him realize that he was alive.

“Oh thank God” he whispered before he turned and looked towards where Qingming and Boya were fighting with the demon.

“I’ll kill him” he snarled, pushing himself to his feet as he pulled out his own gun. He then aimed at the demon and began firing, causing Qingming and Boya to look up and quickly get out of the way as Zhan Yao continued firing. However, before he could spend his last two bullets, the demon waved his hand, sending him flying through the air and crashing to the ground. The demon smirked before he shot into the air, transforming into a human with large leathery wings. Qingming and Boya looked up at the demon in shock before Boya turned to Qingming, who was already reaching out, pressing two fingers to the middle of his browbone. His sigil glowed bright red and soon Boya was shooting into the sky, transforming into his Spirit Guardian form. He then rushed at the demon, forgoing his sword to fight the demon in hand to hand combat like how he did with He Shouyue. Things were going well, Boya was promptly kicking ass when the demon raised his hand, his fingernails transforming into razor sharp claws, and slashed Boya across the chest.

“GAH!!!” Boya cried, the pain so intense it caused him to fall out of the sky.

“Boya!” Qingming screamed, immediately summoning a portal, which Boya fell through before ending up in his arms.

“Boya. Boya!” he exclaimed, cradling the man tightly.

“I’m…fine. I’m fine…” Boya hissed, wincing as his chest continued to bleed. Qingming clenched his hand into fist, letting out a growl.

“You—” he started.

“Qingming” a voice called out, making him look over to see Zhan Yao standing beside him, Boya’s sword in one hand and his gun in another.

“You can…create portals, right?” he asked. Qingming nodded slightly.

“I can…why?” he asked. Zhan Yao looked upwards, glaring at the demon who was smiling down at them.

“I need you to make one for me. One that gets me right in front of the bastard” he growled. Qingming was quiet before he nodded and waved his hand, creating a portal. Zhan Yao clenched Boya’s sword and his gun tightly in his hands before he nodded and rushed through the portal, appearing through another portal that opened up right in front of the demon. Before the demon could even attack, Zhan Yao fired one shot, hitting him in the chest.

“This is for Yutong” he growled. He then fired a second round, hitting the demon in the chest again.

“This is for Boya” he continued. He then dropped the gun as he grabbed Boya’s sword with both hands, raising it above his head.

**“** **AND THIS IS FOR ALL THE CHILDREN YOU MURDERED!”** he screamed before he sliced the demon’s head off. As the demon’s head fell away from its body, Zhan Yao looked at its wide, shocked eyes and huffed.

_‘_ _In the end you showed the same face as your victims…what sick poetic justice’_ he thought to himself as he shut his eyes, feeling himself fall out of the sky.

~*~*~*~*~

A few hours later, Zhan Yao awoke to find himself resting on a matt, a damp cloth on his forehead.

“Ah, you’re awake” a soft voice greeted, making him turn to see Qingming smiling at him. Zhan Yao blinked before he slowly sat up, removing the cloth to clutch at his head.

“Ow…” he murmured. Qingming chuckled softly.

“I bet it hurts…you’ve been asleep for the past two days” he explained. Zhan Yao looked at him in shock.

“Two days?!” he exclaimed. Qingming nodded. Zhan Yao blinked before he sighed.

“What about Boya and Yutong? Are they alright?” he asked. Qingming nodded.

“Boya’s fine. Bai Yutong, on the other hand…he’s still unconscious. Alive, but unconscious” he explained. Zhan Yao’s eyes widened.

“Still?” he whispered. Qingming smiled.

“He was injured rather badly but don’t worry…he’ll wake up soon” he assured, just as Boya walked in, wearing his tattered black skirt and black leggings, a robe draped on his shoulders to reveal his bandaged chest.

“Ah, you’re okay. How are you feeling?” he asked. Zhan Yao nodded.

“I’m fine, thank you” he thanked as he slowly pushed himself to his feet.

“Should you be standing so soon?” Qingming asked as he also stood, walking over to stand by Boya. Zhan Yao nodded.

“I’m alright. Really” he assured before he cleared his throat.

“Do you…know where Yutong is?” he asked. Qingming nodded.

“Follow me” he instructed, motioning for Zhan Yao to follow him to another room where Bai Yutong was laying on a mat with a blanket covering him, his chest rising and falling.

“I’ll give you some time alone” Qingming murmured before he turned and walked out, leaving Bai Yutong and Zhan Yao alone. Zhan Yao then walked over to Bai Yutong and knelt down beside him, reaching out to gently run his fingers through his hair.

“Yutong…wake up soon, okay? I miss you” he murmured. Bai Yutong was silent, making Zhan Yao huff and shake his head.

_‘_ _He probably can’t hear me’_ he thought to himself.

“…miss you…too…” a voice murmured, causing Zhan Yao’s eyes to widen and look down to see Bai Yutong looking blearily at him, a small smile on his face.

“Yutong” he breathed. Bai Yutong smiled weakly.

“Hey Kitten. Boya and Qingming told me what you did…very badass” he murmured. Zhan Yao huffed.

“Oh shut up. It wasn’t anything special…just taking care of the bad guy” he replied. Bai Yutong chuckled before he slowly pushed himself to a sitting position, looking at Zhan Yao fondly before he reached out and pulled Zhan Yao in for a hug, holding him tightly.

“Yutong…should you—” Zhan Yao started when Bai Yutong slowly laid back down, still holding Zhan Yao tightly.

“I’m fine, Kitten. I just want to hold you right now” he murmured. Zhan Yao looked up at him before he huffed and shut his eyes, allowing himself to be held. Meanwhile, in Qingming and Boya’s room, Boya and Qingming were also laying on a mat, Qingming gently touching the bandages on Boya’s chest.

“They’ll scar” he murmured. Boya hummed.

“They will, but it’s alright. I don’t mind having scars if that means I protected you” he murmured. Qingming chuffed.

“Sap” he teased. Boya smiled.

“Maybe” he agreed. Both men laid in silence till Boya hummed.

“That Zhan Yao…I wasn’t expecting that from him” he mused. Qingming chuckled.

“Don’t just a book by its cover, A-Ya. You saw how I reacted when He Shouyue almost killed you…I’m sure that demon hurting Bai Yutong set him over the edge” he stated. Boya hummed as he took Qingming’s head and tucked it under his chin, holding him close.

“Probably” he agreed. 

“They’re each other’s Yin and Yang…just like you and I” Qingming murmured. Boya smiled.

“And one can’t live without the other” he added. Qingming nodded as he snuggled closer to Boya.

“Exactly” he agreed.

~*~*~*~*~

After Bai Yutong and Zhan Yao rested and healed from the…demon encounter, they headed back to the modern world and never heard from Qingming and Boya again. They did try and find the portal that led to the other world, but when they tried and pressed on it, they found it to be just a normal wall.

“Huh…maybe they closed it up” Bai Yutong mused. Zhan Yao hummed.

“Maybe” he agreed. Bai Yutong tsked.

“Too bad. I liked them” he mused. Zhan Yao chuckled.

“Because they reminded you of us?” he teased. Bai Yutong rolled his eyes and socked Zhan Yao in the shoulder, making him hiss.

“Shaddup. Come on, let’s go back” he declared. Zhan Yao nodded and both men then turned away and exited the alley, heading back to S.C.I. 

~*~*~*~*~

At S.C.I., Bai Yutong and Zhan Yao were going over some case files in Bai Yutong’s office when there was a knock on the door.

“Come in” Zhan Yao and Bai Yutong called out. The door then opened and two men stepped inside, shutting the door behind them.

“My my, so busy” a teasing voice called out, making Zhan Yao and Bai Yutong look up to see Qingming and Boya standing before them in their modern clothing.

“What are you two doing here?” Bai Yutong exclaimed. Boya huffed and crossed his arms.

“Why else? A demon got loose” he stated. 

“But no children were harmed this time” Qingming added, a gentle smile on his face. Bai Yutong and Zhan Yao looked at each other before they looked back at Qingming and Boya.

“Count us in” they declared.

**Author's Note:**

> Y'all I have been WAITING to make a S.C.I/The Yin-Yang Master crossover so I'm so happy this prompt was placed in my ask box. I love these four idiots and I really hope you love them too in this fic. Please don't hesitate to leave comments, kudos, bookmark, and subscribe!


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